History

History of Coulomb's discovery
It was known to the ancient Greeks as long ago as 600 B.C. that amber, rubbed with wool, acquired the property of attracting light objects. In describing this property today, we say that the amber is electrified, or possesses an electric charge, or is electrically CHARGED. These terms are derived from the Greek work elektron, meaning amber. It is possible to put an electic charge on any solid material by rubbing it with any other material. Thus, an automobile becomes charged when it moves through the air, a comb is electified in passing through dry hair. Actually intimate contact is all that is needed to give rise to an electric charge. Rubbing merely serves to bring may points of the surfaces nto good contact.

In the field of electricity, unitl the end of the eighteenth century, only the static form was recognized, but in 1731 it was shown, that while some bodies wold conduct electricity, others would not. Thus 'insulation' was possible. In 1747 Benjamin Franklin (1706-90) began to take an interest in electricity and soon observed that electric charges could be drawn off with piculiar faciilty by metal points. He supposed that 'electric fire is a common element' existing in all bodies. If a body had more than its normal share it was called PLUS, (+), if less MINUS, (-).

In 1767 it was suggested by Priestley, that the law of electrical attraction was the same as that of gravitational attraction, namely, the strength of electrical attraction varies as the inverse square of the distance. The first method of measurement applicable to electricity was the action of an electrified of an electrified objects on light suspended bodies such a s threads.

The first effective verification of the law of attraction was made by the French engineer Charles Augustus Coulomb (1736-1806). Using hairs and wires he constructed a torsion balance. The principle was to measure the amount of torsion required to bring a charged pith-ball within various distances of another pith-ball, equally charged with electricity of the same sign and therefore repelling it. Coulomb was the founder of the mathematical theory of electrical action.

http://www.ele.auckland.ac.nz/~kacprzak/Coulomb/coulomb.htm